This invention is related to developments by the present applicant in connection with International Patent Applications PCT/AU89/00275; PCT/AU91/00244; PCT/AU94/00529and PCT/AU94/00569 the contents of which International patent applications are incorporated herein by reference and nominated as split-cycle arrangements. By employing lobed shafts as the means of transmission of linear piston motion to rotary output motion a wide range of varying piston motions can be achieved simply by varying the shape of the lobes. A particular advantage arises in that by appropriate designing of the profiles of the lobes on the shafts the pistons can be controlled in such a manner as to vary their dwell time at any position between top dead center and bottom dead center as well as at those limits of piston motion.
A particular advantage arises where the piston dwell time is extended at its top dead center position to facilitate combustion of the fuel charge while the piston remains at that location to enable maximum energy transmission to the piston and thereby achieve the best possible conversion of combustion energy to engine output power and torque.
In previous disclosures rotary machines of this form have contemplated the use of 50 mm diameter pistons having a 6 mm stroke. Typically the combustion chamber being the volume above the piston at top dead center within the cylinder and head of the engine or machine, has been sized at 2 mm high with a 50 mm bore.
With a 50 mm diameter piston and a 6 mm stroke the swept volume is approximately 11.8 cc for each cycle of motion of the piston while the head volume of the cylinder with the piston at top dead center is approximately 4000 cubic millimeters. The effective cubic capacity of the cylinder is, eg. 10.3 cc. being the swept volume of the cylinder after closing of the exhaust port slit in the cylinder's sidewall as the piston travels toward TDC.